多元碱性氨基酸、肝素及离子强度对猪脾胞质蛋白酪氨酸激酶催化各种底物磷酸化的不同影响。

Diverse effects of poly-basic amino acids, heparin and ionic strength on the phosphorylation of various substrates by cytosolic protein-tyrosine kinase from porcine spleen.

Asahi M, Taniguchi T, Sakai K, Nakamura S, Yamamura H

Department of Biochemistry, Fukui Medical School, Japan.

Int J Biochem. 1990;22(6):635-40. doi: 10.1016/0020-711x(90)90041-z.

Abstract

Effects of poly-basic amino acids, heparin and ionic strength on the activity of cytosolic protein-tyrosine kinase from porcine spleen (CPTK-40) have been studied. 2. Both polylysine and polyarginine stimulated the phosphorylation of [Val5]angiotensin II and E11 G1 (synthetic peptide of EDAEYAARRRG), but could neither stimulate nor inhibit the phosphorylation of random copolymers; poly(EY)4:1 and poly(EAY)6:3:1. 3. Heparin stimulated the phosphorylation of poly(EY)4:1 by 2.5-fold, however, it inhibited those of E11G1, poly(EAY)6:3:1, casein and H2B histone. 4. Elevation of ionic strength of either NaCl, KCl or (NH4)2SO4 stimulated the phosphorylation of poly(EY)4:1 by greater than 5-fold, but inhibited those of casein, tubulin, H2B histone, E11G1 and poly(EAY)6:3:1. 5. These effectors did not change the Km for substrates but increased the Vmax. 6. These results suggest that the effects of poly-basic amino acids, heparin and ionic strength on the activity of CPTK-40 are mainly on the substrates employed rather than on the enzyme itself.

摘要

研究了多碱性氨基酸、肝素和离子强度对猪脾胞质蛋白酪氨酸激酶（CPTK - 40）活性的影响。2. 聚赖氨酸和聚精氨酸均能刺激[Val5]血管紧张素II和E11 G1（EDAEYAARRRG合成肽）的磷酸化，但对无规共聚物聚（EY）4:1和聚（EAY）6:3:1的磷酸化既无刺激作用也无抑制作用。3. 肝素能使聚（EY）4:1的磷酸化增加2.5倍，然而，它抑制E11G1、聚（EAY）6:3:1、酪蛋白和H2B组蛋白的磷酸化。4. NaCl、KCl或（NH4）2SO4离子强度的升高能使聚（EY）4:1的磷酸化增加5倍以上，但抑制酪蛋白、微管蛋白、H2B组蛋白、E11G1和聚（EAY）6:3:1的磷酸化。5. 这些效应物不改变底物的米氏常数，但增加最大反应速度。6. 这些结果表明，多碱性氨基酸、肝素和离子强度对CPTK - 40活性的影响主要作用于所使用的底物而非酶本身。